Covelo climate

Covelo Frost Dates and Growing Season

NOAA 1991-2020 normals for Covelo, 2.6 km from Covelo, elevation 1413 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Covelo. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 23 and the first fall freeze around October 19, a growing season of about 179 days.

Median at 36°F
last May 13, first October 4
Median at 32°F
last April 23, first October 19
Median at 28°F
last March 29, first November 3

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 4May 30May 22May 18May 13May 8May 3Apr 30Apr 26
32°FMay 11May 3Apr 29Apr 26Apr 23Apr 19Apr 14Apr 10Apr 4
28°FApr 18Apr 11Apr 7Apr 2Mar 29Mar 23Mar 16Mar 9Feb 27
24°FMar 17Mar 8Feb 28Feb 24Feb 18Feb 10Jan 31Jan 21Dec 31
20°FFeb 21Feb 8Jan 30Jan 19Jan 12Jan 2Dec 27Dec 18Dec 5
16°FJan 30Jan 20Jan 10Jan 2Dec 28Dec 19Dec 15Dec 8Dec 1

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 21Sep 26Sep 29Oct 2Oct 4Oct 7Oct 11Oct 15Oct 23
32°FOct 2Oct 6Oct 11Oct 15Oct 19Oct 23Oct 28Nov 2Nov 8
28°FOct 14Oct 20Oct 25Oct 31Nov 3Nov 6Nov 12Nov 20Nov 28
24°FOct 29Nov 5Nov 12Nov 19Nov 25Dec 1Dec 4Dec 13Dec 31
20°FNov 13Nov 26Dec 1Dec 7Dec 12Dec 20Dec 27Jan 3Jan 20
16°FDec 1Dec 5Dec 13Dec 17Dec 21Dec 31Jan 4Jan 12Jan 24

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F167159153147141135130123115
32°F204195189184179174169162153
28°F257244235227220213207199188
24°F326313303293282273263253238
20°F365365354343335329320309295
16°F365365365365365365365354338

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
99% of years
20°F or colder
78% of years
16°F or colder
26% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
3,973
Cooling degree days, base 65°F
632
Growing degree days, base 40°F
5,894
Growing degree days, base 45°F
4,359
Growing degree days, base 50°F
3,078
Growing degree days, base 55°F
2,044
Growing degree days, base 60°F
1,239

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January69905
February553015
March498058
April3681121
May20020291
June6380467
July5239699
August5194654
September4587492
October25212236
November547033
December73807

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 2.6 km from Covelo. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00042081 (Covelo). Public domain.